Method for operating an internal combustion engine to transmit power to a driveline

Abstract

A method for operating an engine includes defining a two-dimensional search region based upon an input power transmittable between the internal combustion engine and an electromechanical transmission. The method further includes iteratively dividing the two-dimensional search region into a plurality of subregions based upon one of the input power and the input speed, iteratively determining an engine operating point within each of the subregions, iteratively calculating an operating cost to operate the internal combustion engine and the electromechanical transmission to meet the operator torque request for each engine operating point within each of the subregions, and iteratively identifying the subregion having a minimum operating cost to meet the operator torque request. A preferred engine operating point is determined based upon the engine operating point within the identified subregion having the minimum operating cost to meet the operator torque request.

The invention claimed is: 
     
       1. A method for operating an internal combustion engine mechanically coupled to an electro-mechanical transmission to transmit power to a driveline in response to an operator torque request, the method comprising:
 defining a two-dimensional search region based upon an input power transmittable
 between the internal combustion engine and the electro-mechanical transmission; 
 
 iteratively
 dividing the two-dimensional search region into a plurality of subregions based upon one of the input power and an input speed transmittable from the internal combustion engine to the electro-mechanical transmission, 
 determining an engine operating point within each of the subregions, 
 calculating an operating cost to operate the internal combustion engine and the electro-mechanical transmission to meet the operator torque request for each engine operating point within each of the subregions, 
 identifying the subregion having a minimum operating cost to meet the operator torque request; and 
 
 determining a preferred engine operating point based upon the engine operating point within the identified subregion having the minimum operating cost to meet the operator torque request. 
 
     
     
       2. The method of  claim 1 , further comprising defining a two-dimensional search area based upon input power transmittable between the internal combustion engine and the electro-mechanical transmission. 
     
     
       3. The method of  claim 2 , wherein the two-dimensional search area comprises a range of permissible input speeds and a range of permissible input torques. 
     
     
       4. The method of  claim 2 , wherein the two-dimensional search area comprises a range of permissible input powers and a range of permissible input speeds. 
     
     
       5. The method of  claim 1 , comprising dividing the two-dimensional search region into a plurality of rectangular-shaped subregions. 
     
     
       6. The method of  claim 1 , comprising determining an engine operating point located at a geometric center of each of the subregions. 
     
     
       7. The method of  claim 1 , further comprising controlling the input speed and the input torque of the internal combustion engine based on the preferred engine operating point. 
     
     
       8. The method of  claim 1 , comprising calculating the operating cost based upon vehicle driveability, fuel economy, emissions, and battery usage. 
     
     
       9. The method of  claim 1 , wherein each engine operating point in each subregion comprises a precalibrated normalized engine operating point. 
     
     
       10. The method of  claim 1 , wherein the method comprises one of ten iterations and eleven iterations. 
     
     
       11. A method for operating an internal combustion engine mechanically connected to an electro-mechanical transmission to transmit power to a driveline in response to an operator torque request, the method comprising:
 defining a two-dimensional search region comprising an input torque range and an input speed range transmittable from the internal combustion engine to the electro-mechanical transmission; 
 iteratively
 dividing the two-dimensional search region into a plurality of subregions based upon one of the input torque and an input speed transmittable from the internal combustion engine to the electro-mechanical transmission, 
 determining an engine operating point within each of subregions, 
 calculating an operating cost to operate the internal combustion engine and the electro-mechanical transmission to meet the operator torque request for each of the engine operating points within each of the subregions, 
 identifying the subregion having a minimum operating cost based on the operator torque request; and 
 
 determining a preferred input speed and a preferred input torque for operating the internal combustion engine based upon the iteratively identified subregion having the minimum operating cost based on the operator torque request. 
 
     
     
       12. The method of  claim 11 , further comprising:
 identifying a two-dimensional search area comprising a range of permissible input torques and a range of permissible input speeds transmittable from the internal combustion engine to the electro-mechanical transmission; 
 dividing the two-dimensional search area into the plurality of search regions based upon the input torque and the input speed; 
 determining an engine operating point within each of the plurality of search regions; 
 calculating an operating cost in response to the operator torque request for each of the engine operating points within each of the plurality of search regions; and 
 selecting the search region having a minimum calculated operating cost in response to the operator torque request for the engine operating points within the plurality of search regions. 
 
     
     
       13. The method of  claim 11 , comprising dividing the two-dimensional search region into a plurality of rectangular-shaped subregions. 
     
     
       14. The method of  claim 11 , comprising determining an engine operating point located at a geometric center of each subregion. 
     
     
       15. The method of  claim 11 , further comprising controlling the input speed and the input torque of the internal combustion engine based on the preferred engine operating point. 
     
     
       16. The method of  claim 11 , comprising calculating the operating costs based upon vehicle driveability, fuel economy, emissions, and battery usage. 
     
     
       17. The method of  claim 11 , wherein each engine operating point in each subregion comprises a precalibrated normalized engine operating point. 
     
     
       18. The method of  claim 11  comprising dividing the two-dimensional search region into a plurality of subregions by iteratively alternating dividing search regions based upon input torques and input speeds. 
     
     
       19. The method of  claim 11 , comprising dividing the two-dimensional search region into three subregions. 
     
     
       20. The method of  claim 11 , wherein the method comprises one of ten iterations and eleven iterations.